Arrhythmias
What is ventricular fibrillation?
A series of PVCs in a row, resulting in a heart rate of greater than 100 BPM, is known as ventricular tachycardia (VT). VT is further classified based on the presence or absence of a detectable peripheral pulse. VT with a pulse is treated with antiarrhythmics, whereas pulseless VT is a medical emergency, and advanced cardiac life support (ACLS) should be initiated. Untreated VT can degenerate into ventricular fibrillation (completely disorganized electrical activation of the ventricles) which is always a medical emergency.
How do class II antiarrhythmic drugs work?
Beta-blockers Blocks the sympathetic activity that can trigger an arrhythmia; indirectly blocks calcium channels, which decrease ion conduction speed. Used primarily to slow the rate in ventricular tachyarrhythmias.
Which agents are preferred for ventricular rate control in Afib?
Beta-blockers (preferred) or non-dihydropyridine (non-DHP) calcium channel blockers (CCB) are recommended for controlling ventricular rate in patients with AFib. DO NOT USE NON-DHP CCBS IN HF!!!
What is a boxed warning to dronedarone?
Increased risk of death, stroke and HF in patients with decompensated HF (NYHA Class IV or any class with a recent hospitalization due to HF) or permanent AFib. Class III: primarily block potassium channels
What is a boxed warning for amiodarone?
Pulmonary toxicity and hepatotoxicity. Use only for life-threatening arrhythmias due to toxicities. Proarrhythmic; patients should be hospitalized when loading dose is given.
What are side effects of dronedarone?
QT prolongation, Increased SCr, N/V/D, abdominal pain, diarrhea, bradycardia, asthenia. Unlike amiodarone, dronedarone does not contain iodine, and has little effect on thyroid function.
What is a CI to dronedarone?
concurrent use of strong CYP3A4 inhibitors and QT-prolonging drugs Dronedarone is a moderate inhibitor of CYP2D6, 3A4 and P-gp and a major substrate of CYP3A4. Avoid use with strong inhibitors and inducers of CYP3A4 and with drugs that prolong the QT interval. decrease digoxin dose 50%. Use low doses of statins metabolized by CYP3A4, or use alternate statin. Monitor INR if on warfarin.
What is a CI to flecanide?
structural heart disease (e.g., heart failure, myocardial infarction)
What is a CI to propafenone?
structural heart disease (e.g., heart failure, myocardial infarction)
What is adenosine used for and the t1/2?
t1/2: less than 10 sec Used in paroxysmal supraventricular tachycardia (PSVTs); do not use for converting AFib/Atrial flutter or ventricular tachycardia
What are some DDIS with digoxin?
■ Additive effect with other drugs that decrease HR, including amiodarone, non-DHP CCB, beta-blockers, clonidine and dexmedetomidine (Precedex). ■ Hypokalemia, hypomagnesemia and hypercalcemia increase the risk of digoxin toxicity. ■ Hypothyroidism can increase digoxin levels. ■ Digoxin is a substrate of P-gp. Digoxin levels increase with inhibitors, including amiodarone, dronedarone, quinidine, verapamil, erythromycin, clarithromycin, itraconazole, propafenone and many other drugs. With amiodarone or dronedarone, cut digoxin dose by 50%.
The risk of drug-induced Qtc increases with:
■ Higher doses (the risk is concentration-dependent). ■ Multiple QT-prolonging drugs (additive effect). ■ Reduced drug clearance (e.g., with renal or liver disease). ■ Drug interactions that decrease clearance (with enzyme inhibitors). ■ With low potassium (hypokalemia) and/or low magnesium (hypomagnesemia). ■ Other cardiac conditions; cardiac damage is a risk for arrhythmias, including TdP.
What causes an arrhythmia?
■ The SA node can be firing at an abnormal rate or rhythm. ■Scar tissue from a prior heart attack can block and divert signal transmission. ■ Another part of the heart may be acting as the pacemaker.
What is the therapeutic level for procainamide?
4-10 mcg/mL For NAPA, 15-25 mcg/mL Combined, 10-30 mcg/ml
What is the t1/2 of amiodarone?
40-60 days
What is a Hotler monitor?
A Holter monitor is an ambulatory ECG device that records the heart's electrical activity for 24-48 hours. It is used to detect arrhythmias that are intermittent [i.e., the heart goes in and out of normal sinus rhythm (NSR).]
Where does NSR originate?
A NSR is the normal heart rhythm, with a normal heart rate (between 60 to 100 BPM). A NSR originates (begins) in the sinoatrial (SA, or sinus) node. The SA node is called the heart's natural pacemaker; this is where the electrical signal for a heartbeat begins, and the frequency of the signals determines the pace, or heart rate.
Why is QTc prolongation important?
A QTc interval is considered prolonged when it is > 440 milliseconds (msec), but is more worrisome when markedly prolonged (> 500 msec). Prolongation of the QT interval is a risk factor for Torsade de Pointes (TdP), a particularly lethal ventricular tachyarrhythmia which can cause sudden cardiac death.
What does conduction mean?
The term conduction means to transmit electrical charges (or heat) through a substance.
What is the typical dose of digoxin?
0.125-0.25 mg PO daily
What is the therapeutic range for digoxin in Afib?
0.8-2 ng/mL Remember: Not usually given alone for rate control (used in combination with a beta-blocker or CCB). Antidote: DigiFab
When should anticoagulation be used if going for a cardioversion?
AFib has a high rate of thromboembolism. If the patient is not already using therapeutic anticoagulation, it should be started at least three weeks before cardioversion, and continued for at least four weeks after successful cardioversion to NSR. If using warfarin, the INR should be at the therapeutic level (2-3).
What is non-valvular Afib?
AFib without moderate to severe mitral stenosis or a mechanical heart valve
What is adenosine used for?
Activates adenosine receptors to decrease AV node conduction Used for paroxysmal supraventricular tachyarrythmias (PSVTs).
What is the active metabolite of procainamide?
Active metabolite, N-acetyl procainamide (NAPA), is renally cleared; decrease dose when CrCI < 50 mL/min
What are DDIS with non-DHP CCBS?
Additive effect with other drugs that decrease HR, including amiodarone, digoxin, beta-blockers, clonidine and dexmedetomidine (Precedex). ■ All CCBs, DHP and non-DHP, are CYP3A4 substrates. Use strong CYP3A4 inducers/inhibitors with caution, and in some cases, avoid. Check for drug interactions when starting a CCB and do not use grapefruit with any CCB. ■ Diltiazem and verapamil are substrates of P-gp, and inhibitors of CYP3A4. They can increase the concentration of many other drugs. Patients who take statins should use lower doses of simvastatin or lovastatin or use a statin that is not metabolized by CYP3A4 (e.g., pitavastatin, pravastatin, rosuvastatin).
What is a boxed warning of sotalol?
Adjust dosing interval based on CrCI to decrease risk of proarrhythmia; QT prolongation is directly related to sotalol concentration. CrCI < 60 mL/min: decrease frequency CrCI < 40 mL/min: varies by formulation Non-selective B-Blocker Class III: primarily block potassium channels
What is valvular Afib?
Afib with moderate to severe mitral stenosis or with a mechanical heart valve; long-term anticoagulation with warfarin is indicated
What are some DDIS with amiodarone?
Amiodarone can increase the level of many other drugs; it is an inhibitor of CYP450 2C9 (moderate), 2D6 (moderate), 3A4 (weak) and P-gp. ■ Amiodarone is a substrate of CYP3A4,2C8 and P-gp. Strong/ moderate inhibitors of these enzymes will increase amiodarone and strong/moderate inducers will decrease amiodarone. ■ When starting amiodarone, decrease digoxin by 50% and decrease warfarin by 30 - 50%. Do not exceed 20 mg/day of simvastatin or 40 mg/day of lovastatin; statin levels will increase. Consider use of alternative statin. ■ Additive effect with other drugs that decrease HR, including non-DHP CCB, digoxin, beta-blockers, clonidine and dexmedetomidine (Precedex). ■ Sofosbuvir can enhance the bradycardic effect of amiodarone; do not use together.
What is an arrhythmia?
An arrhythmia is an abnormal heart rhythm, which can cause the heart to beat too slow (bradycardia) or too fast (tachycardia). Any change from the normal sequence of electrical impulses can cause an arrhythmia. When the electrical impulses are too fast, too slow, or erratic, the heart cannot pump blood efficiently, and symptoms can develop.
What is used to diagnose arrhythmias?
An electrocardiogram (ECG) is used to diagnose arrhythmias.
Which key drugs prolong the QTc?
Antiarrhythmics Class I (especially Class la) and Class III Antibiotics Quinolones and macrolides Azole antifungals All except isavuconazonium Antidepressants Tricyclics (e.g., amitriptyline, clomipramine, doxepin) SSRIs (e.g., citalopram, escitalopram); sertraline is preferred in cardiac patients SNRIs, mirtazapine and trazodone Antiemetic agents 5-HT3 receptor antagonists, droperidol and phenothiazines Antipsychotics (most) Chlorpromazine, clozapine, haloperidol, olanzapine, paliperidone, quetiapine, risperidone, thioridazine, ziprasidone Other drugs Donepezil, fingolimod, methadone, tacrolimus
What other drugs can prolong QTc?
Antibiotics: Foscarnet, telavancin and others Oncology drugs: Arsenic, bortezomib, bosutinib, ceritinib, crizotinib, dasatinib, lapatinib, nilotinib, sorafenib, sunitinib HIV drugs: Protease inhibitors (atazanavir, saquinavir) and rilpivirine Other drugs: Alfuzosin, apomorphine, atomoxetine, buprenorphine, chloroquine, diphenhydramine, ezogabine, galantamine, mirabegron, pentamidine, propofol, quinine, ranolazine, sevoflurane, solifenacin, tizanidine
What are side effects with disopyramide?
Anticholinergic effects (e.g., dry mouth, constipation, urinary retention), hypotension.
How are arrhythmias classified?
Arrhythmias are generally classified into two categories based on their location of origin: supraventricular (originating above the AV node) and ventricular (originating below the AV node). Arrhythmias originating in or just below the atrioventricular node are called junctional rhythms, which are less common.
What is Afib?
Atrial fibrillation (AFib) is the most common type of arrhythmia. AFib results from multiple waves of electrical impulses in the atria, resulting in an irregular (and usually rapid) ventricular response. The rapid ventricular rate can result in hypotension and worsen underlying ischemia and heart failure. Due to the disorganized depolarization of the atria, the atria are not able to adequately contract. This results in blood stagnation in the atria, which increases the risk of clot formation. A clot can embolize to the brain (blocking blood in an artery in the brain), which causes a stroke. To reduce clotting risk, patients with AFib may require anticoagulants
How are drugs classified with Vaughan Williams?
CLASS I la: Disopyramide, Quinidine, Procainamide lb: Lidocaine, Mexiletine Ic: Flecainide, Propafenone CLASS II Beta-blockers CLASS III Dronedarone, Dofetilide, Sotalol, Ibutilide, Amiodarone CLASS IV Verapamil, Diltiazem Remember: Double Quarter Pounder, Lettuce Mayo, Fries Please! Because Dieting During Stress Is Always Very Difficult
How do class IV antiarrhythmic drugs work?
Ca-channel blockers, non-dihydropiridines (non-DHP) Used primarily to slow the rate in ventricular tachyarrhythmias (rate control). Negative inotropic effect (decrease contraction force), which can cause cardiac decompensation; do NOT use verapamil or diltiazem with heart failure and reduced ejection fraction (HFrEF).
What is the brand name of verapamil?
Calan, Verelan
What is cardioversion?
Cardioversion is an attempt to return the heart to NSR. Cardioversion is done with drugs or with a medical procedure that delivers a high-energy shock through the chest wall. The shock breaks the incorrect cycle, stops the arrhythmia and allows the sinus node to begin firing again with a NSR. The most common arrhythmia treated with the procedure is AFib.
What is the brand name of diltiazem?
Cardizem, Cardizem CD, Cardizem LA, Tiazac
What is used for stroke prophylaxis?
Clots can form when a patient is in AFib, which can embolize (causing stroke) when the patient returns to NSR. For many patients, it is safer to remain in AFib with rate control than to try to restore NSR. A rate control strategy may require anticoagulation (indefinitely) for stroke prevention. When a rhythm control strategy is chosen, restoration and maintenance of NSR is not guaranteed. Long-term anticoagulation decisions depend on the patient's clot risk.
What are common ventricular arrhythmias?
Common ventricular arrhythmias include premature ventricular contractions (PVCs), ventricular tachycardia and ventricular fibrillation.
What is long-standing persistent Afib?
Continuous AFib of > 12 months
What is persistent Afib?
Continuous AFib that is sustained > 7 days
What is important to correct before giving Ibutilide?
Correct hypokalemia and hypomagnesemia prior to use and throughout treatment. Class III: primarily block potassium channels
When should the dose or interval be decreased?
CrCl < 50 mL/min, decrease dose or frequency. Hold in acute renal failure decrease dose by 20-25% when going from oral to IV
What is the brand name of digoxin?
Digitek, Digox, Lanoxin
What are side effects with quinidine?
Drug-induced lupus erythematosus (DILE), diarrhea (35%), stomach cramping (22%), lightheadedness, N/V, cinchonism (e.g., overdose; symptoms include tinnitus, hearing loss, blurred vision, headache, delirium), rash. Take with food or milk to decrease Gl upset
What are monitoring parameters of amiodarone?
ECG, BP, HR, electrolytes, pulmonary function (including chest X-ray) at baseline and annually, LFTs at baseline and every 6 months, thyroid function at baseline and every 3-6 months, eye exams.
What are some side effects of non-DHP CCBS?
Edema, arrhythmias, constipation (more with verapamil), gingival hyperplasia
What is a warning with dronedarone?
Hepatic failure (especially in the first 6 months), pulmonary disease (including pulmonary fibrosis and pneumonitis)
What are warnings with amiodarone?
Hyper- and hypo-thyroidism (hypo is more common) - amiodarone partially inhibits peripheral conversion of T4 to T3, optic neuropathy (visual impairment), photosensitivity (slate-blue skin discoloration), neurotoxicity (peripheral neuropathy), severe skin reactions (SJS/TEN).
What are side effects of amiodarone?
Hypotension, bradycardia, corneal microdeposits, dizziness, ataxia, N/V, constipation, tremor, skin photosensitivity, drug-induced lupus erythematosus (DILE).
What is a warning with disopyramide?
Proarrhythmic, hypotension, HF, BPH/urinary retention/narrow-angle glaucoma, myasthenia gravis (due to anticholinergic effects). Class 1a antiarrhythmic Mainly blocks Na channels, also K+
What is important to remember about amiodarone administration?
Infusions longer than 2 hours must be administered in a non-polyvinyl chloride (PVC) container such as polyolefin or glass. Premixed Nexterone comes in GALAXY containers (non-PVC and non-DEHP) that can be stored up to 24 months at room temperature. PVC tubing is fine to use. Use a 0.22 micron filter. Incompatible with heparin (flush with saline). Premixed IV bag advantages: longer stability, non-PVC, comes in common concentrations. Slow the infusion rate or discontinue if hypotension or bradycardia occurs.
What are s/sx of digoxin toxicity?
Initial s/sx of toxicity are N/V, loss of appetite and bradycardia. Severe s/sx of toxicity include blurred/double vision, altered color perception, greenish-yellow halos around lights or objects, abdominal pain, confusion, delirium, prolonged PR interval, arrhythmias.
What are CIs to amiodarone?
Iodine hypersensitivity (contains iodine), severe sinus-node dysfunction causing marked decreased HR, 2nd/3rd degree heart block (unless patient has artificial pacemaker), decreased HR that is causing syncope, cardiogenic shock.
How do class III antiarrhythmics work?
K-channel blockers, primarily Amiodarone and dronedarone block K-channels (primarily) and block alpha & beta adrenergic receptors, and Ca & Na channels. Amiodarone is useful for different types of arrhythmias, including AFib, the most common arrhythmia, and is preferentially used in HF. Sotalol blocks K-channels and is a beta-blocker.
What is a boxed warning of dofetilide?
Must be initiated (or reinitiated) in a setting with continuous ECG monitoring, experienced staff and ability to assess CrCI for a minimum of 3 days; proarrhythmic, with QT prolongation. CrCI < 60 mL/min: decrease dose CrCI < 20 mL/min: contraindicated Class III: primarily block potassium channels
How does digoxin work?
Na-K-ATPase blocker Blocking the Na-K-ATPase pump will increase force of cardiac conduction (positive inotrope) and decreases heart rate (negative chronotrope).
How do class I antiarrhythmic drugs work?
Na-channel blockers Reduces the speed of ion conduction through the sodium channels. Proarrhythmic (higher risk of arrhythmia). Negative inotrope potential, which decrease the force of the heart's contraction.
What is the brand name of amiodarone?
Pacerone, Nexterone DOC in HF
What is paroxysmal Afib?
Paroxysmal- AFib that terminates spontaneously or with intervention within 7 days of onset; episodes may recur with variable frequency
What is rate control strategy?
Patient remains in AFib and takes medications to control ventricular rate (HR). Beta-blockers or non-DHP CCBs (sometimes digoxin).
What happens in phase 0?
Phase 0: rapid ventricular depolarization initiates a heartbeat in response to an influx of Na; this causes ventricular contraction (represented by the QRS complex on the ECG) Ventricular contraction
What happens in phase 1?
Phase 1: early rapid repolarization; Na channels close
What happens in phase 2?
Phase 2: plateau in response to an influx of Ca and efflux of K
What happens in phase 3?
Phase 3: rapid ventricular repolarization in response to an efflux of K (represented by the T wave on the ECG) Ventricular relaxation
What happens in phase 4?
Phase 4: resting membrane potential; atrial depolarization occurs (represented by the P wave on the ECG) Atrial contraction
What are boxed warnings for procainamide?
Potentially fatal blood dyscrasias (e.g., agranulocytosis); monitor patient closely in the first 3 months and periodically thereafter. Long-term use leads to positive antinuclear antibody (ANA) in 50% of patients, which can result in drug-induced lupus erythematosus (DILE) in 20-30% of patients. Reserve use for patients with life-threatening ventricular arrhythmias.
What should be done before starting antiarrhythmia medications?
Prior to starting any drug for a non-life threatening arrhythmia, electrolytes and a toxicology screen should be checked to identify reversible causes.
What is a warning of propafenone?
Proarrhythmic Class Ic: block sodium channels
What is a boxed warning to flecanide?
Proarrhythmic effects especially in AFib, do not use in chronic AFib. Class Ic: block sodium channels
What is a warning with quinidine?
Proarrhythmic, hepatotoxicity, hemolysis risk (avoid in G6PD deficiency), can cause positive Coombs test. Class 1a antiarrhythmic Mainly blocks Na channels, also K+
What are examples of supraventricular arrhythmias?
Supraventricular tachyarrhythmias include sinus tachycardia, atrial fibrillation (most common), atrial flutter, focal atrial tachycardias and supraventricular re-entrant tachycardias (formerly known as paroxysmal supraventricular tachycardias or PSVTs). Many patients have ongoing supraventricular arrhythmias (especially atrial fibrillation), without realizing it.
What is a side effect of propafenone?
Taste disturbance (metallic)
What is permanent Afib?
Term used when a joint decision has been made by the clinician and patient to cease further attempts to restore and/or maintain NSR; this is a treatment choice rather than a characteristic of the arrhythmia itself
How are the SA cells different from other myoctyes?
The SA (pacemaker) cells have automaticity, which means that unlike other myocytes, the pacemaker cells initiate their own action potential; they do not require external stimulation. The cells spontaneously depolarize. The action potential is triggered when a threshold voltage is reached.
How does the electrical system work in the heart?
The SA node is a cluster of cells located at the junction of the superior vena cava and the right atrium. The electrical impulse begins in the SA node (1) and travels through the right and left atria (2), which cause the atria to contract. When the signal reaches the atrioventricular (AV) node (3), the electrical conduction slows down before traveling through the bundle of His (4) and into the ventricles. The bundle of His divides into the right bundle branch for the right ventricle (5) and into the left bundle branch for the left ventricle (6). The signal spreads through the ventricles via the Purkinje fibers (7), which causes the ventricles to contract.
What is the cardiac action potential?
The cardiac action potential refers to the movement of ions through channels in the myocytes that cause the electrical impulses in the cardiac conduction pathway. In essence, the action potentials provide the electricity needed to power the heart.
What does the cardiac conduction system do?
The cardiac conduction system is the electrical signaling system that causes the ventricles to contract. The "lub-dub" sounds heard through auscultation (listening to the heart by placing a stethoscope on the chest) are made by the closing of heart valves that occur in sequence with each heartbeat.
What is rhythm control strategy?
The goal is to restore and maintain NSR. Class la, Ic or III antiarrhythmic or electrical cardioversion. ■ If AFib is permanent, avoid rhythm-control antiarrhythmic drugs (risk > benefit).
What is the goal HR in symptomatic Afib?
The goal resting HR is < 80 BPM in patients with symptomatic AFib; however, a more lenient rate-control strategy of < 110 BPM may be reasonable in patients who are asymptomatic and have preserved left ventricular function.
What are causes of arrhythmias?
The most common cause of arrhythmias is myocardial ischemia or infarction. Other conditions resulting in damage to cardiac tissue can cause arrhythmias, including heart valve disorders, hypertension and heart failure. Non-cardiac conditions can trigger or predispose a patient to arrhythmias. These include electrolyte imbalances (especially potassium, magnesium, sodium and calcium), elevated sympathetic states (e.g., hyperthyroidism, infection) and drugs (including illicit drugs and antiarrhythmics).
What is a warning with non-DHP CCBS?
They are class IV antiarrhythmics; they block Ca channels DO NOT USE IN Heart Failure (may worsen symptoms) Only non-DHP CCBs are used as antiarrhythmics.
When is lidocaine used?
Used for refractory VT/cardiac arrest Class lb: block sodium channels. Useful for ventricular arrhythmias only (no efficacy in AFib)
What are symptoms of an arrhythmia?
With most arrhythmias, patients can feel that the heart is beating very fast, or feel a "fluttering" in their chest or think that their heart was "skipping a beat." Symptoms can include dizziness, shortness of breath, fatigue, lightheadedness and chest pain. In severe cases, arrhythmias can lead to syncope, heart failure and death.
